Wordsmith before-and-after technical report

Before—Technical report executive summary (for the public) HIGHWAY CONSTRUCTION AND SCHEDULE An important principle of the Project’s construction methodology is to complete most of the construction activities during the winter months. This strategy offers several advantages:  Allows the use of temporary ice/winter road construction to provide access to borrow sources, without the need to construct more permanent all-weather access roads.  Allows the placement of Highway base material directly onto frozen ground (with geotextile separation layer).  Minimizes potential effects on vegetation and soils adjacent to the actual roadway.

Following each year of winter construction, it is anticipated that most embankment settlement will occur in the top layers of the emplaced borrow material as it thaws, dries and consolidates. Little to no thaw is expected in the lower layers of the embankment, leading to greater Highway stability. This is also expected to reduce potential longer term maintenance problems.

Construction activities will be limited, to the extent possible, to the planned footprint of the Highway. A temporary winter road will run roughly parallel to the alignment and other temporary winter roads, as necessary, will provide access to borrow sources during the winter construction periods.

Before the beginning of construction, the route will be surveyed and staked, and temporary winter roads will be constructed to select borrow sources. Initially snow cats and small dozers will be used to clear snow from the staked footprint. Dozers used for snow clearing will be equipped with mushroom pads to protect the ground surface on the right-of-way. After the route is staked, the snow is cleared, and adequate material is stockpiled at the borrow source, the construction activities will commence.

Construction material will be loaded at the borrow sources using excavators and hauled along the temporary winter roads using both tractor-trailer units and articulated trucks. Material will be placed by end dump and spread with D6 and/or D7 Cats. An initial lift of approximately 300 mm to 400 mm will be placed, followed by smaller lifts, with the final surface elevation being left some 150 mm to 200 mm higher than design to accommodate settlement.

Culvert and bridge installation will proceed along with construction of the Highway. The bridges will typically be prefabricated as single spans that will be installed on binwall abutments. Design, ordering and fabrication of bridges will be undertaken months before the scheduled installation so that shipping schedules are achieved and structures and binwall materials arrive on site in time for installation.

Stream crossings will be accommodated by temporary ice crossings on the adjacent seasonal winter road near the bridge site. Prefabricated bridge structures will be shipped to the individual bridge sites by truck along the constructed portions of the Highway or along the winter road. Each of the four years of

primary roadway construction and installation of drainage structures will be carried out in a similar manner.

Final compaction, adjustments of grade to correct settlements, adjustments to culverts or installation of additional culverts, completion of bridge construction, and placement of surfacing materials on the sections of Highway embankment constructed during the previous winter will be undertaken in the following summer periods.

The Tuktoyaktuk to Source 177 Access Road provides a practical model for the construction of the Highway:  The Highway will be built by local and regional contractors;  Construction will proceed from both the north and south ends;  The Project will take advantage of the winter seasons to develop materials sources and for construction of the main Highway embankment;  Construction will begin by placing geotextile fabric and building forward in lifts of granular material;  Construction will continue in a similar way for each of the four main winter construction seasons;  Bridge construction and culvert installation will generally begin in the winter periods;  Bridge completion and adjustments to culverts previously installed will generally occur during the summer periods;  Certain culverts, such as those to be installed across identified fish habitat, may be installed during the summer periods; and  Final shaping, compaction and placement of granular topping will take place on the constructed Highway embankment in the summer periods.

Subject to completion of the EIRB review process, regulatory approvals and funding, the current generalized construction schedule for the Inuvik to Tuktoyaktuk Highway is outlined in Table 3.

ENVIRONMENTAL CONSIDERATIONS AND MITIGATION MEASURES Climate, Air Quality and Noise Emissions from diesel engine combustion exhaust and dust generated during the construction and future operations phases are considered to be relatively minor. These emissions are expected to be localized, short-term and intermittent.

Highway construction activities will be intermittent, temporary and transient in nature. Most of the noise dust, and air emissions during the construction phase will be associated with equipment operation and blasting activities, if required, to break up the frozen borrow material during excavation. As indicated in Table 3, construction activities that will take place during the summer periods will be mainly related to the completion of bridges, culvert installation, and compaction and grading of the Highway.

The diligent application of the GNWT Guideline for Dust Suppression is expected to be effective in

controlling dust created by summer activities during both the construction and operations phases of the Highway.

While there are no local noise regulations that directly apply to construction noises, the contractors will be directed to apply reasonable mitigation to reduce possible effects associated with construction noise.

These will include adequate maintenance of their construction equipment, including mufflers. Blasting activities, if required, will be timed to avoid periods when sensitive wildlife species are in the area.

Prudent design, best management practices and mitigation will be combined to reduce sound levels during the construction phase.

Examples of prudent design and management practices include:  Limiting construction activity during sensitive periods (based on available background information and recommendations from wildlife monitors) to reduce possible effects on wildlife;  Effective logistics planning to minimize vehicle movements, such as the use of vans or extended cab pick-up trucks to transport workers;  Regular maintenance of equipment and provision of appropriate mufflers for internal combustion engines; and,  Minimizing and managing dust caused by construction materials handling, and the grading and compaction of the Highway.

Permafrost Protection and Climate Change Adaptation The Inuvik to Tuktoyaktuk Highway corridor is located entirely within the zone of continuous permafrost. Ground temperatures are within the range of minus 2˚C to 5˚C. Permafrost is defined as rock or soil material that has remained below 0˚C continuously for two or more years, without consideration of material type, ground ice distribution, or thermal stability. The stability of permafrost and the stability of infrastructure constructed on permafrost depend on maintaining ground temperatures to minimize the thickness of the active layer, and to impede thaw.

A risk-based approach for incorporating climate change into the design of highway infrastructure on permafrost is now recommended practice. This risk-based approach is documented in the national guidelines entitled Development and Management of Transportation Infrastructure in Permafrost Regions published by the Transportation Association of Canada (TAC) in May 2010. The challenge for design and construction over thaw-sensitive permafrost terrain is to balance the capital cost of constructing the Highway, against the long term maintenance implications. The design parameters and construction techniques noted above are based on experience in the area and the case studies and lessons learned as presented in the TAC guideline.

These parameters and techniques take into consideration these risks and provide mitigative approaches in the Highway design. The two most significant elements of the design are the use of nonwoven geotextile fabric between the existing ground and placed construction material, and maintaining a minimum thickness in the material placed, based on terrain type, to insulate the permafrost. Other risk factors that are related to climate uncertainty are precipitation, including both summer rain and winter snow. Key mitigative measures have been incorporated into the design parameters to manage

uncertainty related to future climate trends and extremes in the permafrost region that this Highway will be constructed in. The measures include:  The used of thick embankments that insulate and stabilize the active layer and the use of nonwoven geotextile fabric to assist in maintaining the integrity of the Highway embankment;  The use of appropriately sized culverts to accommodate seasonal overland surface flows where needed; and  Adoption of construction methods that avoid cuts and minimize disturbance of the natural vegetation before fill is placed.

During the Highway operations phase, given the uncertainty of the events associated with climate change, greater vigilance and effort on the part of maintenance operators will be required including, greater effort for spring culvert clearing and fall protection of culverts and drainage structures, more frequent inspections, and monitoring of the performance of the infrastructure.

As with the design parameters and construction techniques noted above, the mitigative measures proposed for the operations phase of the Highway are based on experience in permafrost regions and the risk-based approach that is documented in the TAC May 2010 guide for Development and Management of Transportation Infrastructure in Permafrost Regions.

After—Technical report executive summary (for the public) Section 1. Permafrost protection is the central planning focus for the Highway The key environmental focus for constructing the Highway is protecting permafrost, and the project is designed around this goal. This will continue to be the focus for its long-term use and maintenance. The following technical decisions and steps support that goal:

The project will follow the TAC Guide for permafrost regions The project will follow the TAC May 2010 guide for Development and Management of Transportation Infrastructure in Permafrost Regions. Specifically, this means:      

using non-woven geotextile fabric between the existing ground and construction material to prevent road material from migrating into the permafrost using a minimum thickness (which varies based on terrain type) of construction material to insulate the permafrost thick embankments to insulate and stabilize the roadway nonwoven geotextile fabric to help maintain integrity of the embankments appropriate-sized culverts where there could be seasonal overland surface flows avoiding cuts into and minimizing disturbance to the natural vegetation during construction

Most construction will take place in winter months to reduce impact An important principle of the Project’s construction methodology is to complete most of the construction activities, including gathering sand and gravel, during the winter months. This strategy offers several advantages:   

allows the use of temporary ice/winter road construction to provide access to borrow sources, without the need to construct more permanent all-weather access roads allows the placement of Highway base material directly onto frozen ground minimizes potential impact on vegetation and soils adjacent to the actual roadway

In summer periods, contractors will do minor construction. This includes final compacting, adjusting grade and culverts after settling, installing additional culverts, completing bridges, and surfacing sections of Highway embankment that were constructed the previous winter.

Thaw is expected only in top layers of road materials Following each year of winter construction, we anticipate some settling in the top layers of the sand and gravel as it thaws, dries and consolidates. Little to no thaw is expected in the lower layers, leading to greater Highway stability and reduced potential longer-term maintenance.

The Project will limit construction to the planned footprint of the Highway as much as possible A temporary winter road will run roughly parallel to the alignment. Other temporary winter roads will access sand and gravel sources during the winter construction. Before beginning construction, the route will be surveyed and staked. Contractors will load construction material at the source using excavators and move it on the temporary winter roads with both tractor-trailers and articulated trucks.

Construction will not use traditional “cut and fill” methods The cut and fill methods used on southern highways would damage protective surface vegetation and organics, which could lead to thawing permafrost below vegetation layers. Instead, construction will place frozen fill materials on frozen tundra in winter months. This will cause the least disturbance of vegetation and permafrost.

Culverts and bridges will go in as the Highway is being constructed Culvert and bridge installation will proceed along with construction of the Highway. Bridges will typically be prefabricated as single spans to be installed on binwall abutments. We will order bridges design and fabrication months before scheduled installation to meet shipping schedules and ensure materials arrive on site on time.

Construction crews will cross streams near the bridge site when the streams are frozen. Trucks will bring in prefabricated bridge structures to the sites along the new Highway or the winter road.

Section 2. Project plans include uncertainty about climate change We have considered uncertainty about climate change in design and maintenance plans To respond to the fact that it is difficult to predict the impact of climate change:    

The project will follow the risk-based approach for building and maintaining roads in permafrost regions, as Transportation Association of Canada (TAC) i recommends.

When the Highway is complete, we will require maintenance contractors to monitor the road and culverts more frequently (spring and fall) to assess and respond to possible climate changes.

Other risk factors related to climate uncertainty are levels of summer rain and winter snow.

The TAC document gives guidance on balancing costs of constructing the Highway with long-term maintenance.

See appendix X for more information.

Section 3. Issues related to climate, air quality and noise will be minor Emissions will be short-term and temporary We assess the level of emissions from diesel engines during construction as relatively minor, as are emissions after the highway is in use. During construction, contractors will reduce the number of vehicles by transporting workers in vans or extended cab trucks.

Dust will occur primarily in winter and contractors will manage dust in summer months Breaking up and excavating frozen borrow material will be the primary cause of dust. Some dust will come from grading and compacting. All these activities will take place mainly in winter months. In the limited construction in summer periods (see Table 3), contractors will keep dust to a minimum by following the GNWT Guideline for Dust Suppression.

Contractors will limit noise levels There are no local noise regulations that directly apply to construction. However, we will direct contractors to mitigate noise by:   

avoiding blasting when sensitive wildlife species are in the area (based on recommendations from wildlife monitors and available information on wildlife behaviour) maintaining equipment, including mufflers using best design and management practices

Section 4. More detail about construction design and sequence Dimensions, location, and specifications Length of proposed highway

137 km

Length of Alternative 3 (2010 Minor Realignment)

Reduced by approx. 2 km to meet Husky Lakes setback

Location

Entirely within the ISR (Figure 1)

Percentage of highway on Inuvialuit private lands

51.5 % or approx. 71 km Regulated and administered by the Inuvialuit Lands Administration (ILA)

Percentage of highway on Crown lands

48.5% or approx. 68 km Regulated and administered by Indian and Northern Affairs Canada (INAC)

Dimensions of finished highway

Two lanes, 8 to 9 m wide with 3:1 side slopes

Bridge requirements

8 stream crossings that will likely require bridges

Bridge types

Single-lane, short-span

Management of smaller streams and water flow

Culverts

Sand and gravel source

Taken from sources near the Highway

Geometry of design

See Table 2

Design of typical cross section

Figure 2

Specifications of finished highway Available seasons for use

Year round by passenger vehicles and haul trucks

Speed limit

80 km/hour

Weight limits for haul trucks

Defined in Northwest Territories highway regulations

Standards that will apply to highway operation

GNWT DOT standards and guidelines for public highways that GNWT DOT also manages and operates

Construction schedule Appendix XX outlines the generalized construction schedule for the Inuvik to Tuktoyaktuk Highway, subject to the EIRB review process, regulatory approvals and funding. The main principles are:       

local and regional contractors will build the Highway. construction will proceed from both north and south ends. construction will begin by placing geotextile fabric and build forward in sections of sand and gravel. construction will follow the same pattern for each of four main winter construction cycles. bridge construction and culvert installation will begin in winter periods and complete or have minor rework during summer periods. contractors may install certain culverts, such as those in identified fish habitat, during the summer. final shaping, compacting, and placing gravel will be done in summer periods.

1198 words (Approx. 37% reduction. Some content was moved in and out of this section)

i